-7x-2y=-13
x-2y = 11 get x alone
x-2y+2y=11+2y
x= 2y+11 substitute into 1st equation
-7 (2y+11) -2y =-13
-14y -77 -2y = -13
-16y -77 = -13
-16y -77 + 77 = -13 + 77
-16y = 64
-16y/-16 = 64/-16
y = -4
substitute in the 2nd equation
x =2y +11
x = 2(-4) + 11
x = -3 + 11
x = 3
Check work
-7(3) -2(-4) = -13
-21 + 8 = -13
-13 = -13
3 -2(-4) = 11
3 + 8 = 11
11 = 11
